Lennox furnace error code 403

About Lennox Furnace Error Code 403

A furnace (specifically the gas valve) fails to wait for confirmation from the remote control before signaling to the furnace. Lennox furnace error code 403 is a legitimate state representing that the burner has automatically shut down due to an unsafe condition.

The search for error code 403 led to the Lennox support page where it provided a possible cause of ‘Possible causes of error code 403: A sensor has detected high pressure in the gas valve assembly.’ As typing, instability, and fluctuations lead to high pressure in the gas valve some more checks were done to verify whether this is the safe cause based on sensors performance in relation to such affliction and supply provided by other systems. The sensing takes lightly as there is no occupancy or electricity time period and as safety factors check out, it will go ahead and restart automatically after 10 minutes have elapsed since shut down, but if there are any destabilization or fluctuations again within 10-min.

Error code 403 is quite dangerous and can lead to the shutdown of the self-cleaning procedure if not rectified in time. In such a circumstance, an engineer must investigate the cause of this error code and resolve it as soon as possible.

The engineers are usually trained to diagnose faulty parts and make changes in order to fix the issue when an error code like 403 is displayed by the Lennox furnace. Any individual who’s trying to fix this error without proper knowledge of heater components may risk damaging it further.

Some general steps that will fix the Lennox furnace after displaying Error Code 403 are — shutting off all electric fuel circuitry for at least one minute, then resetting all protective device sensor assemblies, then repeating the prior step after waiting for one minute before isolating the system again and disconnecting.

In general, an error code 403 on your Lennox furnace alerts you of an issue involving the motherboard – whether that’s malfunctioning sensors, incomplete factory reset at some point, bugs in system memory, or corrupted firmware in some way or another.

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